/**
 * @file Name: 5.cpp
 * @author: Fenghuwuyu
 * @version: 1.0
 * @brief:
 * @date: Fri 09 Apr 2021 03:49:27 AM PDT
 */

#include<iostream>
int main()

/**
 * Class Hierarchies:
 *
 * Use virtual and pure can make a good father class.
